Cosmos from Seed

Last summer I planted about 75-100 Cosmos seeds (followed directions on package) only about 2 flowers ever bloomed. Located in Central KY. The seeds were from several different retail nurseries.. Any suggestions? I have bought several packs of seeds and plan to plant those around the first week in May. Any suggestions would be greatly appreciated. Thank you!

Did the seedlings sprout and grow and most of them never bloomed, or did they never sprout at all? Assuming they sprouted but didn't bloom...when did you sow them? You mention planting them last summer, so if you actually waited until summer to start them that's probably the issue--you need to start them earlier so that they have time to grow and then bloom before cold weather comes along and kills them. Otherwise if you planted them early enough and the sprouted and grew but never bloomed then maybe not enough sun, too much/little water, too much/little fertilizer, etc.

Thanks for the response. I planted the seeds & they never sprouted. I bought several packets of seeds from several different companies. I planted them the 2nd week of May. Thanks !

Unfortunately there are a ton of things that can cause seeds to not come up so it may be hard to figure it out for sure this long afterwards. Maybe the area doesn't get enough sun, maybe there was too much/little water while they were trying to germinate, maybe they were buried too deep in the soil, maybe they were washed away by rain, maybe they were eaten by birds...and probably a number of other possibilities as well! The seeds could have been bad too, but I think that's less likely especially since you mention that you got seeds from a few different places.

I'd guess that either they didn't get steady enough moisture during germination or they were planted too deep--they really don't require much cover.

Here's a link with some info about germinating Cosmos sulphureus. Even if you're trying to grow C. bipinnatus, the germination instructions would be almost identical.
http://aggie-horticulture.tamu.edu/plantanswers/flowers/cosmos/cosmos.html
(scroll down to the paragraph sandwiched between the Gloria & Candy Stripe images)

Wildseed Farms http://shop.wildseedfarms.com/Cosmos/products/3/ can be a good place to get seed and rudimentary cultural information. The one time I tried C. sulphureus in TX, I bought from them, planted it in heavy clay, kept it evenly moist until it was knee-high, and it worked perfectly; I had flowers for the whole season.

In my garden here I noticed that feral cosmos with flowers smaller than a dime grow and bloom in sandy soil, so I tried cosmos again, sowing it in early March. We've had a number of frosts since then, so I'm not sure whether it's dead or alive. Joping it hasn't sprouted yet, but will soon.